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Forum Discussion

1qaz's avatar
1qaz
Icon for Nimbostratus rankNimbostratus
May 08, 2020

I want to get the source port but it was changed by F5?

Hi,I have a question for help: I have a VS1 on BIGIP 3900, I want the source port of the client to be kept, but I observed that the client'port all be changed by F5: (tmos)# show sys connection cs-...
application delivery
BIG-IP
LTM
Mayur_Sutare's avatar
Mayur_Sutare
Icon for MVP rankMVP
May 08, 2020

There may be couple of reasons for such behavior. Actually i was trying to figure out it one-by-one but i could have done it in one go (my mistake).

With CMP enabled state, F5 may change source port  to keep the client-side and server-side traffic on the same TMM. Here F5 ignores Preserve setting.

 

https://support.f5.com/csp/article/K14358

 

Mayur

  • 1qaz's avatar
    1qaz
    Icon for Nimbostratus rankNimbostratus
    May 08, 2020

    thanks to Mayur!I think as you said, CMP may be the real reason of all this. I think I can insert the source address and source port in the http header, and get the source port of the client by irule. Thanks again!

     

    when HTTP_REQUEST { 

      HTTP::header insert Cliet_IP_port [IP::client_addr]:[TCP::client_port]

    }